My "corn, potatoes and onions" Weber 26 3/4" is a real beauty, but the grates are getting a bit worn. I'm debating on whether to shell out the $50 for new ones from Weber (admittedly a bargain), or just keep the old ones.

Basically, my grates are still intact, but quite rusty. Think I'm good just oiling them up and keeping them clean...or is it important to get the new ones?

I just bought some new grates for my Weber and have decided that this needs to become a yearly affair, at least for the cooking grate. It was nice to have a nice really clean grate and light fish that didn't stick, with some grill marks to boot. I would invest in a new grate and keep it well oiled to avoid the rust.

I've had my grill for about four years now and the grates are really showing it. One of the key spot welds at the hinge has broke loose and the grate is starting a good layer of rust this year. They make a heavier grate for the Patio Classic, than the stock one that it came with, which costs a few dollars more. I'll be replacing mine soon and will definately buy the heavy duty one.

As long as your ordering new ones anyway, may I sugest an experiment with your current ones?
If you have a self-cleaning oven, throw your grates and flavorizer bars in the oven and clean. This bakes off anything that doesn't belong. Brush off and reseason with shortening or oil.
As long as you haven't actually rusted through, this should preserve and somewhat restore your grates as much as can be done. It never hurts to have a spare set.

When your new grates arrive be sure to season well.

Keep 'em hot.
Keep 'em clean,
& keep 'em lubricated and they should last a long time.